1. Field of the Invention
The present invention relates to a multi-function actuator capable of preventing vibration. More particularly, the multi-function actuator of the present invention can prevent the vibration of a vibration unit during sound generation in response to user's switch selection.
2. Description of the Related Art
A multi-function actuator generally means a small sized vibration and sound-generating apparatus that functions to output audible sound from electrically received audio signals or previously inputted bell or melody. Such multi-function actuators are mounted on various mobile communication systems such as a mobile phone, pager, gaming system and headset.
FIG. 1 illustrates a conventional multi-function actuator, as will be described hereinafter.
A conventional multi-function actuator 100 includes a hollow housing 110, a sound generating diaphragm 121 fixed by the outer circumference to the top of the housing 110, a voice coil 122 cylindrically wound and fixed to the bottom of the diaphragm 121, a vertically magnetized magnet 123, a yoke 131 forming a magnetic circuit together with the magnet 123, a weight 133 forming a vibrator together with the yoke 131 and upper and lower leaf springs 132 and 132′ supporting the vibrator at the top and the bottom, respectively.
Lines of magnetic force from the N pole of the magnet 123 are directed to the S pole of the magnet 123 through the voice coil 122 and the yoke 131 in their order thereby forming a magnetic field. The voice coil 122 functions as a speaker to generate sound by using magnetic flux from the magnetic circuit including the magnet 123 and the yoke 131.
In the meantime, application of low frequency voltage to the voice coil 122 induces vertical movement to the vibrator, which further includes the weight 133 together with the magnet 123 and the yoke 131 of the magnetic circuit, thereby generating vibration.
The conventional multi-function actuator generates vibration in a relatively lower frequency range but sound in a relatively higher frequency range based upon resonant frequency.
However, when used as mobile communication devices or for other purposes, the conventional multi-function actuator has a problem in that sound generation is accompanied with vibration because the frequency range of audio signals gradually expands into the low frequency range.
In particular, the afore-described conventional actuator 100 is prone to have various problems associated with controlling such as overlapping in frequency, etc., since it is designed to generate both of sound and vibration by inputting frequency signals into a single signal source or the voice coil 122.
FIG. 2 illustrates another conventional actuator which additionally has a vibration coil to improve some of the above problems, as will be described hereinafter.
The conventional actuator 200 includes a cylindrical outer frame 210, a sound unit 220, which comprises a diaphragm 221, a voice coil 222 and a sound magnet 223, and a vibration unit 230, which comprises a yoke 231, a vibration coil 232 and a vibration magnet 233. The sound unit 220 and the vibration unit 230 are placed inside the cylindrical outer frame 210
In the outer periphery of the outer frame 210, there is provided a terminal plate for supplying external voltage to the voice coil 222 and the vibration coil 232.
In the inner periphery of the outer frame 210, there are provided an upper leaf spring 240 and a lower leaf spring 240′. An annular acoustic magnet 223 is mounted on the bottom of the upper leaf spring 240 and the top of the lower leaf spring 240′. An inner frame is coupled with the top of the sound magnet 223 and the upper leaf spring 240.
The voice coil 222 is connected with the terminal plate. When a voltage having a predetermined frequency or more is supplied to the voice coil 222, the voice coil 222 is vertically vibrated by an electromagnetic force produced through the interaction between a magnetic field generated from the sound magnet 223 and an electric field generated around the voice coil 222.
This vertically vibrates the diaphragm 221 coupled integrally with the voice coil 222 thereby producing sound.
In the meantime, the vibration coil 232 is connected with a different terminal plate. When a voltage having a predetermined frequency or more is supplied from this terminal plate to the vibration coil 232, the yoke 231 is vertically vibrated by an electromagnetic force produced through the interaction between a magnetic field of the vibration magnet 233 and an electric field generated around the vibration coil 232. The vibratory force of the yoke 231 is transmitted to the outer frame 210 through the upper and lower leaf springs 240 and 240′, and the vibratory force of the outer frame 210 is transmitted to the outside.
This as a result generates vibration to inform call incoming.
Although the above actuator is so structured that the sound unit 220 is separated from the vibration unit 230 in order to avoid any interference between them, this still has a problem of vibration since it is impossible to prevent the reaction of the vibration unit 230 in the event that the diaphragm 221 of the sound unit 220 is vibrated to generate sound.
Accordingly, a multi-function actuator, which can prevent vibration resulting from sound generation in response to user selection, has been required in the art in order to prevent such problems.